Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Invest Ophthalmol Vis Sci. 2021 Oct 4;62(13):11. doi: 10.1167/iovs.62.13.11.
This exploratory study aimed to investigate the morphological and pathological alterations of the meibomian gland (MG) with the Staphylococcus aureus crude extracts (SACEs) treatment.
Mouse MG explants were cultured and differentiated with or without SACEs for 48 hours. Explant's viability and cell death were determined by thiazolyl blue tetrazolium bromide (MTT) assay and TUNEL assay. MG morphology was observed by Hematoxylin and Eosin staining. Lipid droplet production was detected by Nile Red staining and LipidTox immunostaining. The pro-inflammatory cytokines were detected by ELISA. The relative gene and protein expression in MG explants was determined via quantitative RT-PCR, immunostaining, and immunoblotting. The components of the SACEs were analyzed by immunoblotting and silver staining.
Our findings demonstrated that the SACEs treatment induced overexpression of keratin 1 (Krt1) in the ducts and acini of MG explants, accompanied by a decrease in viability and an increase in cell death in explants. Furthermore, the SACEs treatment dose-dependently increased the levels of TNF-α, IL-1β, and IL-6 in MG explants. The SACEs treatment induced activation of the nuclear factor kappa B (NF-κB) and AIM2 (absent in melanoma 2)/ASC (apoptosis-associated speck-like protein containing a caspase recruitment domain) inflammasome signaling pathway in explants. Further investigation showed expression of the key adipogenesis-related molecule peroxisome proliferator-activated receptor γ was decreased after SACEs treatment. However, no change was found in the lipid synthesis of MG explants after treatment with the SACEs. Staphylococcal enterotoxins B (SEB) was detected in the SACEs. SEB induced the overexpression of Krt1 and IL-1β in ducts and acini of MG explants.
Our findings confirm that Staphylococcus aureus induced hyperkeratinization and pro-inflammatory cytokines expression in MG explants ducts and acini. These effects might be mediated by SEB. Activation of the NF-κB and AIM2/ASC signaling pathway is involved in this process.
本探索性研究旨在研究金黄色葡萄球菌粗提物（SACEs）处理后，睑板腺（MG）的形态和病理改变。
将鼠 MG 外植体与或不与 SACEs 培养和分化 48 小时。噻唑蓝（MTT）测定法和 TUNEL 测定法测定外植体活力和细胞死亡。苏木精和伊红染色观察 MG 形态。尼罗红染色和 LipidTox 免疫染色检测脂滴生成。酶联免疫吸附试验（ELISA）检测促炎细胞因子。通过定量 RT-PCR、免疫染色和免疫印迹测定 MG 外植体中的相关基因和蛋白表达。免疫印迹和银染分析 SACEs 的成分。
我们的研究结果表明，SACEs 处理诱导 MG 外植体的导管和腺泡中角蛋白 1（Krt1）过度表达，同时外植体活力降低，细胞死亡增加。此外，SACEs 处理剂量依赖性地增加了 MG 外植体中 TNF-α、IL-1β 和 IL-6 的水平。SACEs 处理诱导外植体核因子 kappa B（NF-κB）和 AIM2（黑色素瘤 2/ASC（含半胱氨酸的天冬氨酸蛋白水解酶募集域）凋亡相关斑点样蛋白）炎症小体信号通路激活。进一步研究表明，SACEs 处理后，关键脂肪生成相关分子过氧化物酶体增殖物激活受体 γ 的表达减少。然而，SACEs 处理后，MG 外植体的脂质合成没有变化。在 SACEs 中检测到葡萄球菌肠毒素 B（SEB）。SEB 诱导 MG 外植体导管和腺泡中 Krt1 和 IL-1β 的过度表达。
我们的研究结果证实，金黄色葡萄球菌诱导 MG 外植体导管和腺泡中的过度角化和促炎细胞因子表达。这些作用可能是由 SEB 介导的。NF-κB 和 AIM2/ASC 信号通路的激活参与了这一过程。
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